Emergency Radiobioassay Method for Determination of 90 Sr and 226 Ra in a Spot Urine Sample Baki B. Sadi,* ,† Allison Fontaine, ‡ Daniel McAlister, § and Chunsheng Li † † Radiation Protection Bureau, Health Canada, 775 Brookfield Road, A.L. 6302D, Ottawa, ON K1A 1C1, Canada ‡ Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada § Eichrom Technologies LLC, 1955 University Lane, Lisle, Illinois 60532, United States * S Supporting Information ABSTRACT: A new radiobioassay method has been developed for simultaneous determination of 90 Sr and 226 Ra in a spot urine sample. The method is based on a matrix removal procedure to purify the target radionuclides from a urine sample followed by an automated high performance ion chromatographic (HPIC) separation of 90 Sr and 226 Ra and offline radiometric detection by liquid scintillation counting (LSC). A Sr-resin extraction chromatographic cartridge was used for matrix removal and purification of 90 Sr and 226 Ra from a urine sample prior to its introduction to the HPIC system. The HPIC separation was carried out through cation exchange chromatography using methanesulfonic acid (75 mM) as the mobile phase at 0.25 mL/min flow rate. The performance criteria of the method was evaluated against the American National Standard Institute ANSI/HPS N13.30-2011 standard for the root mean squared error (RMSE) of relative bias (B r ) and relative precision (S B ) at two different spiked activity levels. The RMSE of B r and S B for 90 Sr and 226 Ra were found to be satisfactory (≤0.25). The minimum detectable activity (MDA) of the method for 90 Sr and 226 Ra are 2 Bq/L and 0.2 Bq/L, respectively. The MDA values are at least 1/10th of the concentrations of 90 Sr (190 Bq/L) and 226 Ra (2 Bq/L) excreted in urine on the third day following an acute exposure (inhalation) that would lead to an effective dose of 0.1 Sv in the first year. The sample turnaround time is less than 8 h for simultaneous determination of 90 Sr and 226 Ra. R apid and efficient sample preparation for matrix removal, preconcentration, and purification of radionuclides from urine continues to be a priority research area in radiobioassay for internal radiation dose assessment. In the event of a radiological/nuclear (R/N) accident at a nuclear power plant or a terrorist activity using a radiological dispersal device (RDD), improvised nuclear device (IND), and/or strategic nuclear weapon, it may be necessary to rapidly screen a large number of people for radiological contamination. 1 Following an initial triage for external radiological contamination, further screening for internal contamination may be required. Rapid screening for internal contamination is essential because the relevant medical intervention (for example, chelation therapy) should be undertaken as early as possible. 2 Radiobioassay (i.e., measure- ment of radionuclides in the whole body, target organ, or excreta, such as urine) combined with biokinetic models and dosimetric models can be used to estimate radiation dose from internal contamination. Urine is a commonly used specimen for in vitro radiobioassay. Traditional radiobioassay methods for determination of radionuclides in urine are often tedious and time-consuming and may not be suitable in an R/N emergency where high sample throughput is required. 3,4 In traditional urine radiobioassay methods (for internal dose assessment for occupational exposure), a 24-h urine sample (1200-1600 mL) is subjected to wet digestion to mineralize the radionuclides, coprecipitation to separate and preconcen- trate them from the urine matrix, and further purification of target radionuclides by chromatography or solvent extrac- tion. 5-8 In an R/N emergency, it will be more effective to collect a spot urine sample (50-100 mL) rather than a 24-h collection. To reduce sample preparation time, recent efforts have focused on using a spot urine sample and employing preconcentration via streamlined coprecipitation without any wet digestion, followed by separation and purification using radionuclide selective multiple stacked extraction chromato- graphic cartridges/columns. 9-13 Rapid radiobioassay methods have also been developed in which initial wet digestion and coprecipitation steps have been eliminated, and smaller volumes (<50 mL) of acidified raw urine samples are processed directly using extraction chromatography. 14,15 In order to Received: May 8, 2015 Accepted: July 13, 2015 Published: July 13, 2015 Article pubs.acs.org/ac © 2015 American Chemical Society 7931 DOI: 10.1021/acs.analchem.5b01752 Anal. Chem. 2015, 87, 7931-7937